Powertop can help your Linux laptop / netbook battery life but if you want to increase it drastically, you'll have to do some further tweaking.
I recently came across an amazing website called Less Watts which should really help you save some watts without installing any additional software:
LessWatts.org is about how you can save real watts, however you use Linux* on your computer or computers.
If you're a geek who likes to tweak things and want to increase your computer's battery life, head over to Less Wats and start hacking!
